Sealing and severing device for packaging machines



Nov. 16, 1965 FIG I FIG 2 s. 1. BRATT ETAL 3,218,218

SEALING AND SEVERING DEVICE FOR PACKAGING MACHINES Filed Sept. '7, 1962.I nl

Sven [Brafi and Tar e Kara'er INVE NTORS BY W @2 4 M AT TOR N EYS UnitedStates Patent 3,218,218 SEALING AND SEVERING DEVICE FOR PACKAGINGMACHINES Sven I. Bratt and Terje Karder, Partille, Sweden, assignors toKisab Aktieboiag, Goteborg, Sweden, a joint-stock company of SwedenFiled Sept. 7, 1962, Ser. No. 221,975

Claims priority, application Sweden, Sept. 11, 1961,

9,015/ 61 9 Claims. (Cl. 156-530) This invention relates to a device inpackaging machines for effecting sealing and simultaneous severing ofpackages transversally to the feeding direction of the packages by meansof two rotating rolls resiliently pressed against each other and againstopposite sides of the package sheet material and having envelopesurfaces designed to form narrow, mutually co-operating sealing zonesparallel to the axes of the rolls, one of two co-operating zones beingprovided with a knife and the other with a striking bar having a countersurface perpendicular to the knife, both members extending all along thelength of the zones.

A considerable inconvenience of prior machines of this type consists inthat the contact pressure of the rolls againstthe package sheet materialis reduced during the severing operation due to the fact that the knifeand the striking bar are bearing to a considerable part of the contactpressure during the severing operation, which will give rise to poorseals on both sides of the line of cutting. Compensation by increasingthe pressure on the rolls to a value required for good sealing duringthe cutting operation will result in too great contact pressure duringthe sealing operation. In order to avoid these irregularities insealing, packaging machines of similar types having two sealing jawswhich are movable into engagement with opposite sides of the packagematerial as well as along the feeding direction of the packages areoften provided with a knife which is slidably fitted in a slot in one ofthe jaws which knife when severing the package material is arranged toenter a slot in the other jaw aligned with the slot in the first jaw.The sealing performed by means of such a sealing and severing device isnot entirely satisfactory because no sealing at all is obtained near theline of cutting where the slots are located.

The object of the invention is, therefore, the provision of a packagemachine in which said inconveniences are avoided in a simple andsatisfactory manner.

According to the invention a sealing and severing device for packingmachines is provided for effecting sealing and simultaneously therewithsevering of packages transversally to the feeding direction of thepackages by means of two rotating rolls resiliently pressed against eachother and against opposite sides of the package sheet material andhaving envelope surfaces designed to form narrow, mutually co-operatingsealing zones parallel to the axes of the rolls, one of two co-operatingzones being provided with a knife and the other with a striking barhaving a counter surface perpendicular to the knife both membersextending all along the length of the zones, characterized in that theknives and/or the striking bars are slidably fitted in radial slots inthe rolls and are provided with end portions protruding from the endwalls of the rolls which end portions at the severing moment move intoengagement with and are pressed radially outwards by means of two camsurfaces which are journaled in the frame movable in the directionperpendicular to the tangential plane of the rolls against the urge ofresilient members.

Thus the rolls are operated independent of the knife and the strikingbar and it is possible to adjust the contact pressure of the rolls to avalue which is suitable for ob- Patented Nov. 16, 1965 taining a fullysatisfactory seal. During the severing operation a suitably adaptedforce is supplied to the knife and the striking bar by means of the camsurfaces without influencing the contact pressure of the rolls.

In a sealing and severing device according to the invention it ispossible to obtain an improved severing and a reduction of the forcenecessary for the severing in a very simple manner, as will be apparentin the following, by imparting to the knife and the striking bar,respectively, a tilting motion at severing in which case the edge of theknife and the striking bar are suitably formed slightly crooked, so thatthese members touch each other in a point of tangency which due to thetilting is displaced along the line of severing.

A specific embodiment of the invention is shown by way of example in theaccompanying drawings in which:

FIGURE 1 shows the rolls in longitudinal section and arms locatedoutside the end walls of the rolls supportingthe rolls and the camsurfaces, and

FIGURE 2 shows a view of one of the end portions of the rolls, which isequal to the other end portion.

The rolls 1 and 2 are in this embodiment arranged one above the other.The lower one 1 is rotatably journaled directly in the frame 3 by meansof two arms 4 which are fixedly mounted in the frame on both sides ofthe roll and on which the shaft pivots 5 of the roll are journaled. Theshaft pivots 6 of the upper roll 2 are rotatably journaled on two leverarms 7 located on both sides of the roll, which arms are pivoted on theframe 3 by means of the shaft 8. On this shaft 8 two further arms 9 arepivoted on both sides of the roll 2, each of which arms supports aroller 11 rotatably journaled on the shaft 10. The rolls are providedwith envelope surfaces, which form mutually co-acting sealing zones 12,13 and 14, 15, and along the middle lines of the zones the rolls areprovided with radial slots 16, 17, 18, 19 which extend straight acrossthe width of the rolls. In the bottom of the slots 16 and 18 strikingbars 20 are fixedly mounted and in the slots 17 and 19 knives 21 areslidably fitted having end portions protruding from the end walls of theroll 2. The free ends of the arms 6 and 9 are resiliently attached tothe arms 4 by means of rods 22 and 23 and compression springs 24 and 25the pressure of which is adjustable by means of nuts 26 and 27.

As the rolls 1 and 2 are rotated by means of a drive mechanism, notshown, a series of the units to be packaged 28 placed in spaced-apartrelationship and enveloped by a flexible, sealable sheet wrappermaterial is advanced between the rolls 1 and 2 in synchronism with therotation of the rolls and with the edge portions of the sheet materialpressed between the cylindrical end portions of the rolls. The radius ofthe rolls 1 and 2 and the number of sealing zones are so adapted thatseals are obtained intermediate the individually packaged units. Atevery sealing operation the end portions of a knife 21 pass by under therolls 11, which are located in a distance from the shaft 7 so adaptedthat the knife is pressed outwards and brought into engagement with thestriking bar simultaneously present under the knife and is pressedagainst this by means of the rollers under compression of the springs25.

In the embodiment shown the striking bars 20 are countersunk somewhatbelow the surface of the sealing zones which facilitates the cuttingoperation in that the package sheet material when moved downward towardsthe striking bar 20 by the knife 21 and clamped along the edges of theslots 16, 18 becomes subjected to tension simultaneously with thecutting. In a further embodiment of the invention it is possible toimpart to the knife a tilting motion in the plane of the knife in a verysimple way by 10- cating the rollers somewhat displaced in relation toeach other in the direction of rotation of the rolls.

The knives 3 or the striking bars are suitably formed slightly crookedin this case so that a knife and a striking bar touch each other in acontact point which due to the tilting of the knife continuously isdisplaced across the seal.

The invention is, of course, not limited to the embodiment shown butshould be regarded as including modifications and variations thereofwithin the scope of the invention as claimed. Thus, the arms 9 may beprovided with fixedly mounted cam surfaces instead of rollers 11.Further the roll 1 and the striking bars 20 may be resiliently journaledin the same manner as the roll 2 and the knives 21. Besides, in somecases, the rolls may be arranged to make a reciprocating motion ofturning eventually in combination with bringing the rolls apart duringthe backward motion of the rolls.

We claim:

1. A sealing and severing device for a wrapper with spaced contentstherein comprising a frame, two uniformly rotating rolls in said framebetween which said wrapper is fed, a spring yielding bearing arrangementfor said rolls, a sealing member on each roll having a radiallyextending slot therein dividing said members into each two spacedsealing zones extending parallel to the longitudinal axis of each roll,a knife blade slidingly mounted in said slot of one of said members, astriking bar mounted in the other of said members, said knife blade andstriking bar severing said wrapper between the seals made by said zonesbetween said spaced contents, said knife blade having the ends thereofprotruding from the end Walls of its roll, means mounted in said framein resilient bearing members cooperating with said ends for operatingsaid knife blade for displacing it radially outwards in said slot.

2. A sealing and severing device for a wrapper with spaced contentstherein comprising a frame, two uniformly rotating rolls in said framebetween which said wrapper is fed, a spring yielding bearing arrangementfor said rolls, a sealing member on each roll having a radiallyextending slot therein dividing said members into each two spacedsealing zones extending parallel to the longitudinal axis of each roll,a knife blade mounted in said slot of one of said members, a strikingbar slidingly mounted in said slot of the other of said members, saidknife blade and striking bar severing said wrapper between the sealsmade by said zones between said spaced contents, said striking barhaving the ends thereof protruding from the end walls of its roll, meansmounted in said frame in resilient bearing members cooperating with saidends for operating said striking bar for displacing it radially outwardsin said slot.

3. A sealing and severing device for a Wrapper with spaced contentstherein comprising a frame, two uniformly rotating rolls in said framebetween which said wrapper is fed, a spring yielding bearing arrangementfor said rolls, a sealing member on each roll having a radiallyextending slot therein dividing said members into each two spacedsealing zones extending parallel to the longitudinal axis of each roll,a knife blade slidingly mounted in said slot of one of said members, astriking bar slidingly mounted in said slot of the other of saidmembers, said knife blade and striking bar severing said Wrapper betweenhe seals made by said zones between said spaced contents, said knifeblade and striking bar having the ends thereof protruding from the endwalls of said rolls, means mounted in said frame in resilient bearingmembers cooperating with said ends for operating said knife blade andstriking bar for displacing them radially outwards in said slots.

4. A sealing and severing device as claimed in claim 1, wherein saidmeans coacting with the ends of said knife blade are positioned mutuallydisplaced in the direction of rotation of the rolls to impart to theknife blade a tilting motion in the plane of said slot at the severingoperation.

5. A sealing and severing device as claimed in claim 4, wherein the edgeof the knife blade is slightly crooked in the plane of said slot.

6. A sealing and severing device as claimed in claim 1, wherein saidmeans cooperating with said ends are mounted each on a spring-loadedlever arm pivoted on a shaft parallel to the axes of said rolls.

7. A sealing and severing device as claimed in claim 6, wherein one ofsaid rolls is journaled on two springloaded lever arms pivoted on saidshaft.

8. A sealing and severing device as claimed in claim 7, wherein the freeend portions of all the lever arms are lengthened and resilient membershaving means for adjusting the springforce are mounted between thelengthened portions of said lever arms and said frame.

9. A sealing and severing device as claimed in claim 1, wherein saidmeans cooperating with said ends comprise freely rotatable rollerseccentrically journaled in relation to said rolls.

1. A SEALING AND SEVERING DEVICE FOR A WRAPPER WITH SPACED CONTENTSTHEREIN COMPRISING A FRAME, TWO UNIFORMLY ROTATING ROLLS IN SAID FRAMEBETWEEN WHICH SAID WRAPPER IS FED, A SPRING YIELDING BEARING ARRANGEMENTFOR SAID ROLLS, A SEALING MEMBER ON EACH ROLL HAVING A RADIALLYEXTENDING SLOT THEREIN DIVIDING SAID MEMBERS INTO EACH TWO SPACEDSEALING ZONES EXTENDING PARALLEL TO THE LONGITUDINAL AXIS OF EACH ROLL,A KNIFE BLADE SLIDINGLY MOUNTED IN SAID SLOT OF ONE OF SAID MEMBERS, ASTRIKING BAR MOUNTED IN THE OTHER OF SAID MEMBERS, SAID KNIFE BLADE ANDSTRIKING BAR SEVERING SAID WRAPPER BETWEEN THE SEALS MADE BY SAID ZONESBETWEEN SAID SPACED CONTENTS, SAID KNIFE BLADE HAVING THE ENDS THEREOFPROTRUDING FROM THE END WALLS OF ITS ROLL, MEANS MOUNTED IN SAID FRAMEIN RESILIENT BEARING MEMBERS COOPERATING WITH SAID ENDS FOR OPERATINGSAID KNIFE BLADE FOR DISPLACING ITRADIALLY OUTWARDS IN SAID SLOT.